1. Field of the Invention
The present invention relates generally to expert systems and, more particularly, to systems and methods for solving problems related to performance or operation of a servo system during its integration into a machine.
2. Description of Related Art
Servo systems are complex mechanisms to be inserted or incorporated into machines. Due to the complexity of many servo systems, the potential causes of servo performance or operational issues may span many technical disciplines. Individuals who select a particular servo system for use in a specific machine frequently need help improving servo performance and diagnosing servo operational problems. Since most servo system users cannot spend the time necessary to develop the skills and expertise for diagnosing and correcting servo problems, expert assistance is usually required. Indeed, the solution to a particular servo performance problem is often counter-intuitive.
Many servo problems occur during the integration phase, i.e., after a machine has been designed, but before it has been placed into service. The integration phase is to be distinguished from both the design and the troubleshooting phases of a servo system""s life span. Servos are usually designed by mechanical engineers who design to avoid traditional mechanical problems such as improper clearances, catastrophic failure due to stress, fatigue and normal wear. However, other servo problems such as long response times, instability, mechanical resonance, inaccurate positioning, excessive torque perturbations, and excessive generation of noise can seriously degrade performance or operation of a machine. These types of problems often are not detected until after the servo design has been completed. By such a time, the machine has often been built and awaits being put into service.
Engineers who seek advice during the integration phase of servo design are faced with a unique set of limitations; the problems must be corrected with minimal design changes and, usually, in a short period of time because the machine has been built and is usually due to be placed into service soon. Engineers are not dealing with traditional design problems such as selecting materials, topology or mechanisms. These decisions must be made before the machine prototype can be built. Also, engineers are not dealing with traditional troubleshooting that involves isolating problems on presumably well-designed machines that have been in service for a significant amount of time. Problems solved by troubleshooting do not even occur until after a machine has been placed in service, e.g., problems caused by wear or component failure.
It has long been known that servo system users need an alternative to human-based assistance. Telephone conversations with an expert are often inadequate, and obtaining on-site help is usually impractical because it is expensive and time consuming. Some servo users have developed procedures to solve certain classes of problems without relying on an expert. For example, some servo system manufacturers and users have developed flowcharts to help diagnose faults. This flowchart method of problem solving may be appropriate when only binary (i.e., yes/no) decision-making processes are required to diagnose the problem, e.g., eliminating a drive error or finding an open electrical connection. However, binary decision-making processes alone cannot be used to diagnose and solve problems related to servo performance since those problems are often combinations of multiple root causes that occur in varying degrees. Problems encountered during servo system integration usually have subjective (i.e., non-binary) representations. Thus, a more robust form of diagnostic and problem solving tool is required.
An expert system can often address problems based on several causes which occur in varying degrees. The field of expert systems was developed to provide non-human expert assistance. For example, physicians and psychiatrists use expert systems to some extent to aid in patient diagnosis. U.S. Pat. No. 5,660,183 to Chiang et al. discusses such an expert system. Engineers use expert systems during the design and troubleshooting phases of a product or process life-cycle. U.S. Pat. No. 5,557,775 to Shedletsky discloses such a use. However, most expert systems are used either to help design an object or process, or to troubleshoot problems that have developed after the object or process has been designed and put into operation.
It is therefore an object of the present invention to provide an expert system which can serve as an alternative to human-based assistance by providing non-human expert assistance in diagnosing and correcting common servo performance problems which are detected when a machine or prototype is first made operational, or shortly thereafter.
It is another object of the present invention to provide an expert system which can address several independent and subjective problems simultaneously.
It is a further object of the present invention to provide an expert system capable of quickly providing a range of several potential modifications to address a particular observed machine condition.
The present invention overcomes the shortcomings of conventional servo system integration techniques and conventional expert systems. Specifically, the invention features systems and methods which allow a user to input information describing a particular servo system, and then receive an ordered set of possible actions the user can implement to solve the observed problems.
Certain embodiments of the present invention include a method and system that presents a description of one or more general servo conditions and a plurality of severity designations for the one or more general servo conditions, receives data descriptive of a machine""s specific state, the machine having a servo, and generates a recommendation containing an instruction as to modification of the machine or servo.
Another embodiment of the present invention is a system comprising a memory having embodied therein: data descriptive of one or more general servo conditions and a plurality of severity designations for the one or more servo conditions, and data descriptive of a plurality of recommendations each describing one or more modifications to a machine having a servo system; a central processing unit in communication with the memory, the processor configured to receive data descriptive of a machine""s specific state including one or more general servo conditions and a corresponding severity designation, the machine having a servo, and to select one or more of the plurality of recommendations based in part on the data descriptive of the machine""s specific state.
A further embodiment of the invention comprises an expert system for recommending a modification to a machine having a servo system, the expert system comprising a server configured to receive data descriptive of one or more servo system problems and to present data descriptive of an ordered set of solutions to the one or more servo system problems.